[OSM-dev] PBF HeaderBlock optional?

[Scott Crosby]

On Tue, Dec 21, 2010 at 6:47 PM, Anthony <osm at inbox.org> wrote:
> On Tue, Dec 21, 2010 at 11:08 AM, Scott Crosby <scott at sacrosby.com> wrote:
>> On Mon, Dec 20, 2010 at 6:01 PM, Scott Crosby <scott at sacrosby.com> wrote:
>>> Yes. That is an osmosis bug. That header block is required.
>>
>> I would like to clarify this slightly. There must be an OSMHeader
>> block before the first OSMData block, however, the OSMHeader block
>> does not have to be the first block in the file. Also, parsers should
>> ignore fileblocks types that they do not understand.
>
> And can there be more than one OSMHeader block, possibly with
> different requirements, for instance concatenated streams?

Yes. Although no program currently generates such streams, I think a
parser should handle a stream with multiple OSMHeader blocks in a
best-effort fashion. I don't see any real risk of issues. AFAIK, all
readers support all currently defined required features, and there are
no ideas right now that might change the status quo.

Scott